Open-circuit fault diagnosis method and system for converter

Abstract

The invention, which relates to the field of circuit fault diagnosis, discloses an open-circuit fault diagnosis method and system for a converter, thereby diagnosing open-circuit faults of one kind ofconverters having the same bridge arm structures and thus improving the versatility of the diagnosis method and reducing the maintenance difficulty and cost of the converter effectively. The method comprises: selecting circuit topologies of any bridge arm of a to-be-detected converter in a normal working sate and an open-circuit fault state and establishing a first consistency model; according tothe first consistency model, building a fourth consistency model that is suitable for the normal working sate and the open-circuit fault state of the converter; simulating the operating state of theconverter by using the fourth consistency model, calculating a voltage residual based on an actual phase voltage value and an estimated phase voltage value, and constructing a residual evaluation function according to the voltage residual; comparing the output value of the residual evaluation function with a set residual detection threshold; and determining an open-circuit fault of the bridge armunder the condition of meeting a set fault occurrence condition by the comparison result.

Description

technical field [0001] The invention relates to the field of circuit fault diagnosis, in particular to an open circuit fault diagnosis method and system for a converter. Background technique [0002] Converter is a commonly used power conversion device, which is often used in traction drive control systems and renewable energy conversion systems. These applications have very strict requirements on the reliability and safety of converter operation, but the power Devices often operate under the conditions of high voltage, high frequency and high current, so their switching losses are very large, and long-term uninterrupted operation may easily lead to failure of power devices. Statistics show that power devices are the most prone to failures in converters, which basically account for about 50% of the total system failures in many applications. Power device faults mainly include open-circuit faults and short-circuit faults. For short-circuit faults, fast fuses are often added ...

AI Technical Summary

Problems solved by technology

Power device faults mainly include open-circuit faults and short-circuit faults. For short-circuit faults, fast fuses are often added to the system for protection. When a short-circuit fault occurs, the fuse will blow at a very fast speed, and then turn into an open-circuit fault situation; When an open-circuit fault occurs, if it is not dealt with in time, its adjacent power devices will bear greater voltage and current, which will easily lead to secondary faults and seriously affect the reliability and safety of the converter and even the power conversion system.

[0003] The converter is generally composed of multiple identical converter bridge arms, and its structure has obvious consistency, but the current diagnosis of the open circuit fault of the converter is often aimed at different structures (such as two-level or three-level ) converters or open-circuit faults in different parts of the same converter (such as rectifiers or inverters), different fault diagnosis methods are used, and the generality of the diagnosis methods is poor

There are not many researches on consistent methods for open-circuit fault diagnosis of traction converters

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